Nginx 1.2.1 + aio + Debian 7

Hello,
I've compiled nginx 1.2.1 under Debian 7 Wheezy --with-file-aio, however when i set aio on; and directio 4m; website works, but can not load large files from the hdd. Do I have to tune debian somehow? When i enabled sendfile on; then website started serving large files (0.1GB-10GB). So does AIO work or not? How can i confirm it?

user www-data;

pid /var/run/nginx.pid;

worker_priority -10;
worker_processes 4;
worker_cpu_affinity 00001000 00000100 00000010 00000001;
worker_rlimit_nofile 20000;

events {
worker_connections 65536;
multi_accept on;
use epoll;
worker_aio_requests 256;
}

aio on;
directio 4m;
output_buffers 1 8m;

sendfile on;
#sendfile_max_chunk 8m;
send_timeout 60s;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 20s;
keepalive_requests 50;
reset_timedout_connection off;
client_max_body_size 10G;
client_body_buffer_size 8M;
types_hash_max_size 2048;
server_tokens off;

open_file_cache max=200000 inactive=60m;
open_file_cache_valid 30m;
open_file_cache_min_uses 2;
open_file_cache_errors off;

proxy_buffer_size 6M;
proxy_buffers 4 2M;
proxy_busy_buffers_size 6M;
proxy_max_temp_file_size 0;

Thanks.